A related art image reading apparatus is provided. In the related art image reading apparatus, a line start signal designating the reading start time of a line image is input to a line sensor at a predetermined cycle, the line sensor or document is moved at a constant velocity, a line image data of each line is generated, and the read image data representing the read image of the whole document is generated.
A related art flatbed-type image reading apparatus has been also known, in which a reading pulse (line start signal) is input to a line sensor at a time interval corresponding to the movement time of the line sensor as the distance of one line, and line image data for each line are generated.
Further, an related art image reading apparatus has been also known, which outputs a time signal (line start signal) to an image sensor on the basis of a signal output from an encoder unit detecting the rotation amount of a motor driving a carriage on which the image sensor is mounted.